package com.hmdp.utils;


import cn.hutool.core.lang.UUID;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;


import java.util.Collections;
import java.util.concurrent.TimeUnit;

public class SimpleRedisLock implements ILock{

    private String lockName;
    private StringRedisTemplate stringRedisTemplate;

    private static final String KEY_PREFIX = "lock:";
    private static final String ID_PREFIX = UUID.randomUUID().toString(true)+"-";
    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    static {
        UNLOCK_SCRIPT = new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        UNLOCK_SCRIPT.setResultType(Long.class);
    }

    public SimpleRedisLock(String lockName, StringRedisTemplate stringRedisTemplate) {
        this.lockName = lockName;
        this.stringRedisTemplate = stringRedisTemplate;
    }

    @Override
    public boolean tryLock(long timeoutSec) {
        // 获取线程标识
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        Boolean success = stringRedisTemplate.opsForValue().setIfAbsent(KEY_PREFIX+lockName,threadId,timeoutSec, TimeUnit.SECONDS);
       // 只要有自动拆箱就有可能存在空指针异常
        return Boolean.TRUE.equals(success);
    }


    // 基于 Lua 脚本实现原子性操作
    @Override
    public void unlock() {
        // 调用 Lua 脚本
        stringRedisTemplate.execute(UNLOCK_SCRIPT,
                Collections.singletonList(KEY_PREFIX+lockName),
                Collections.singletonList(ID_PREFIX+Thread.currentThread().getId())
         );
    }




   /* @Override
    public void unlock() {
        // 获取线程标识
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        // 获取锁中 id
        String id = stringRedisTemplate.opsForValue().get(KEY_PREFIX+lockName);
        if (threadId.equals(id)){
            // 一致释放锁
            stringRedisTemplate.delete(KEY_PREFIX+lockName);
        }
    }*/
}
